Self-locking devices

ABSTRACT

An improved self-locking device for locking a movable structural member to a stationary structural member, or to another movable structural member, or for unlocking the same, comprising a rotatable self-locking cam and an actuating means therefor; the rotatable self-locking cam being rotatably mounted on a first structural member and having (1) an arcuate surface thereon, capable of preventing movement of a movable structural member in a first or opening direction, and (2) a cam surface thereon, capable of moving the movable structural member in the first or opening direction; and the actuating means being capable of rotating the self-locking cam in an angular direction whereby the cam surface contacts an ear on the movable structural member to forcibly move it in the first or opening direction, while the arcuate surface is being simultaneously moved out of the way of the movable structural member, due to the angular rotation of the self-locking cam, to permit the movement of the movable structural member in the first or opening direction to unlock the movable structural member from the first structural member; means mounted on the first structural member to contact the self-locking cam and limit the rotation thereof; and then, the ear on the movable structural member being subsequently capable of rotating the self-locking cam in an angular direction opposite to that of the first angular direction, whereby the movable structural member returns to its original locked position, wherein it is prevented from moving in the first or opening direction by the arcuate surface on the rotatable self-locking cam.

This patent application is a continuation-in-part of our co-pendingpatent application, Ser. No. 676,509, filed Apr. 13, 1976.

FIELD OF THE INVENTION

The present invention relates to improved self-locking devices, and moreparticularly is concerned with improved self-locking devices which arecapable of very simply and very easily locking a movable structuralmember to a stationary structural member, or to another movablestructural member, and subsequently very simply and very easilyunlocking such structural members in an uncomplicated fashion. Even moreparticularly, the present invention relates to improved self-lockingdevices for locking or for unlocking access members, such as covers,doors, panels and the like, which provide access or entry to variousenclosures of all kinds and types.

BACKGROUND OF THE INVENTION

Self-locking devices for locking various structural members together andfor subsequently unlocking them have been known and used for many yearsand there are many commercially successful self-locking devices whichare currently available on the open market. However, there is always aneed and a desire to make these self-locking devices simpler and easierto operate, as well as more economical to manufacture and easier tomaintain in use and in service. Also, there is always a need and adesire to make these self-locking devices more automatic and moreself-actuating in their operation and more fool-proof and tamper-proofin their service and use.

PURPOSES AND OBJECTS OF THE INVENTION

It is therefore a principal purpose and object of the present inventionto provide an improved self-locking device which is very simple and veryeasy to operate, very economical to manufacture, very easy to maintainin service and in use, automatic and self-actuating in its operation,and substantially fool-proof and tamper-proof in its use.

BRIEF SUMMARY OF THE INVENTION

It has been found that such principal purposes and objects of thepresent invention, as well as other principal purposes and objects whichwill become clear from a further reading and understanding of thisspecification, may be achieved by providing a self-locking device forlocking a movable structural member to a stationary structural member,or to another movable structural member, or for unlocking the same,comprisinng a rotatable self-locking cam and an actuating meanstherefor: the rotatable self-locking cam being rotatably mounted on afirst structural member and having (1) an arcuate surface thereon,capable of preventing movement of a movable structure member in a firstor opening direction, and (2) a cam surface thereon, capable of movingthe movable structural member in the first or opening direction; and theactuating means being capable of rotating the self-locking cam in anangular direction whereby the cam surface contacts an ear on the movablestructural member to forcibly move it in the first or opening direction,while the arcuate surface is being simultaneously moved out of the wayof the movable structural member, due to the angular rotation of theself-locking cam, to permit the movement of the movable structuralmember in the first or opening direction to unlock the movablestructural member from the first structural member; means mounted on thefirst structural member to contact the self-locking cam and limit therotation thereof; and then, the ear on the movable structural memberbeing subsequently capable of rotating the self-locking cam in anangular direction opposite to that of the first angular direction,whereby the movable structural member returns to its original lockedposition, wherein it is prevented from moving in the first or openingdirection by the arcuate surface on the rotatable self-locking cam.

Although the present inventive concept will be described and illustratedin greater particularity with reference to above-ground connection andsplice enclosures or other terminal enclosures for buried communicationor power cable installations, or the like, it is to be appreciated thatthe principles of the present inventive concept are equally applicableto other enclosures of all types and kinds, including, for example,chambers, compartments, chests, rooms, or other receptacles orcontainers, which it is desired or required to close and lock. As usedherein, therefore, the terms "structural member", "enclosure member", or"access member" are intended to include such elements as covers, panels,doors, walls, barriers, frames, and the like, which may be slidable, orrotatable, or hinged, or otherwise constructed, which are used to formthe elements of enclosures or are used to provide entry or access tosuch enclosures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following specification and accompanying self-explanatorydrawings, there are described and illustrated preferred embodiments ofthe present inventive concept, but it is to be realized that theinvention, in its broader aspects, is not to be construed as limited tosuch preferred embodiments as disclosed, except as determined by thespirit and the scope of the appended claims.

Referring to the accompanying self-explanatory drawings,

FIG. 1 is a fragmentary perspective view of a part of the back cover andthe lower front cover of an above-ground terminal enclosure for buriedcommunication cable or power installations, employing the principles ofthe present invention, with the upper front cover and the cap removed;

FIG. 2 is a perspective view, showing the upper front cover of theterminal enclosure of FIG. 1, as removed from the back cover thereof;

FIG. 3 is a perspective view, showing the cap of the terminal enclosureof FIG. 1, as removed from the top thereof;

FIG. 4 is a fragmentary, schematic and diagrammatic elevational view ofa preferred embodiment of the improved self-locking device of thepresent invention in its fully closed and locked position, as viewedfrom within the interior of the terminal enclosure;

FIGS. 5, 6 and 7 are fragmentary, schematic and diagrammatic elevationalviews of the preferred embodiment of the improved self-locking device ofthe present invention, as illustrated in FIG. 4, but progressingsuccessively and sequentially to other opening positions wherein (1)slack has been removed from between cooperating parts; (2) the terminalenclosure is still locked but is partially open; and (3) the terminalenclosure is unlocked and is ready to be opened fully, respectively;

FIG. 8 is a fragmentary cross-sectional view, taken on the line 8--8 ofFIG. 4, show the internal construction of the actuating means whichrotates the self-locking cam and hub of the improved self-locking deviceof the present invention;

FIG. 9 is a fragmentary side elevational detail view, showing theannular cup washer employed in the application of the principles of thepresent invention;

FIG. 10 is a fragmentary end elevational detail view, showing incross-sectional view, the annular cup washer of FIG. 9, taken on theline 10--10 of FIG. 9, in the direction indicated by the pair of arrows;

FIG. 11 is a side elevational detail view, showing the actuating tubularshoulder rivet employed in the application of the principles of thepresent invention, before it has been assembled and secured to theself-locking cam and hub;

FIG. 12 is an end elevational detail view, showing the actuating tubularshoulder rivet of FIG. 11, as viewed from the shank end;

FIG. 13 is a fragmentary perspective showing of the operating ears andthe related portions of the movable upper front cover of the terminalenclosure of the present invention;

FIG. 14 is a fragmentary, schematic and diagrammatic elevational view ofanother preferred embodiment of the improved self-locking device of thepresent invention, in its fully closed and locked condition, as viewedfrom within the interior of the terminal enclosure, with some partsomitted (particularly a rotation-limiting plate) for purposes of clarityof illustration of the rotatable self-actuating and self-locking cam;

FIGS. 15 and 16 are fragmentary, schematic and diagrammatic elevationalviews, similar to that illustrated in FIG. 14, but progressingsuccessively and sequentially to other more advanced opening positionswherein (1) the terminal enclosure is still locked but is partiallyopen; and (2) the terminal enclosure is unlocked and is ready to beopened fully, respectively;

FIG. 17 is a detailed, elevational view of the rotation-limiting platewhich was omitted from FIGS. 14-16, this view being taken from theexterior of the terminal enclosure, with the back cover and parts of theactuating shaft removed in order to show more clearly the relationshipof the self-locking cam to the rotation-limiting plate; and

FIG. 18 is a fragmentary, cross-sectional plane view taken in ahorizontal plane through the center of rotation of the self-locking cam,in the angular position of FIG. 14, showing the assembly and theoperating relationship of the various cooperating elements.

The various scales to which these Figures have been drawn are not thesame in all cases; some have been drawn to larger scales and others havebeen drawn to smaller scales. The smaller elements of the improvedself-locking devices have been drawn to larger scales in order to bringout more clearly the details of such smaller elements. The largerelements of the self-locking device have been drawn to smaller scales,primarily for accommodation purposes to fit the size of the sheet ofdrawing material.

Additionally, some of the detail views of the smaller elements have beenrotated slightly out of their normal operating positions in order tomore clearly illustrate the detailed constructions of such smallerelements.

FIGS. 1 to 3 have been drawn approximately to 1/6× scale. FIGS. 4through 7 are drawn approximately 5× scale. FIGS. 9 to 12 have beendrawn approximately 3× scale. FIG. 13 has been drawn approximately 4×scale.

Additionally, it is to be observed that in some of the drawings, such asFIGS. 4 through 7, for example, some of the lesser important parts andelements have been omitted, purely in the interests of providing aclearer and more easily understandable illustration. And finally, FIGS.17 and 18 represent the self-locking device, as it would appear ifmounted on the left hand side of the back cover, as contrasted to FIGS.14 through 16, which represent the self-locking device, as it wouldappear if mounted on the right hand side of the back cover. This hasbeen done primarily for purposes of clarity of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With particular reference to FIGS. 1 through 3 of the drawings, there isshown an above-ground terminal enclosure comprising a partially-buriedback-cover 10; a partially-buried lower front cover 12; an upper front14 which is removable from the back cover 10 and the lower front cover12; and a cover 16 which is adapted to fit over to cover and protect theupper ends of the back cover 10 and the upper front cover 14 and to keeprain, snow, sleet, etc., from the interior of the terminal enclosure,when it is assembled and in service and use.

The back cover 10 is a substantially U-shaped channel member andcomprises a rear wall 18 and a pair of laterally extending side flanges20, 22 which are approximately at right angles to the rear wall 18.

The lower front cover 12 is also a substantially U-shaped channel memberand comprises a lower front wall 24 and a pair of laterally extendingside flanges 26, 28 which are approximately at right angles to the lowerfront wall 24.

The back cover 10 and the lower front cover 12 are adapted to fittogether and to be bolted together, or otherwise secured to each other,as shown, to form an elongated, lower enclosure compartment in whichcommunication or power cables, terminals, and related equipment iscontained.

The lower front cover 12 may be separated from the back cover 10, ifdesired or required, but, once the communication or the power cables,terminals, and other equipment and parts have been installed and thelower front cover 12 and the back cover are secured together andpartially buried in the ground to a depth, such as shown in FIG. 1, thelower front cover 12 and the back cover 10 are normally not separatedfor service, maintenance, inspection, or for other purposes.

The upper front cover 14 is similarily a substantially U-shaped channelmember and comprises an upper front wall 30 and a pair of laterallyextending side flanges 32, 34 which are substantially at right angles tothe upper front wall 30. The upper front cover 14 has approximately thesame horizontal-plane cross-section as the lower front cover 12 and,when assembled together in use, forms generally an extension of thelower front cover 12. The upper front cover 14 is adapted to fittogether with the upper portion of the back cover 10 to define anelongated upper enclosure compartment in which communication or powercables, terminals, and related equipment and parts is contained.

The upper front cover 14 and the back cover 10 are not permanentlysecured together, as by bolting, but are adapted to be held together bymeans including a pair of laterally projecting lanced tabs, pins, orshoulder rivets 36, 36 and a pair of cooperating guiding and lockingslots 38, 38 and to be locked in such a configuration, or opened, bymeans about to be described more fully hereinafter. Such opening of theinterior of the terminal enclosure is, of course, accomplished byunlocking and removing the upper front cover 14 from the back cover 10.

A third lanced tab or shoulder rivet 36' and an angularly disposedguiding and locking slot 38' are provided on the back cover and on thelower portion of the upper front cover 14, respectively. As noted inFIG. 2, the guiding and locking slot 38' is disposed at approximately anangle of about 45° upwardly with respect to the edge of the flange 32 ofthe movable upper front cover 14.

Such angularity of the guiding and locking slot 38' is desirable at thelower end of the movable upper front cover 14, inasmuch as, during theopening of the terminal enclosure, the lower portion of the upper frontcover 14 is allowed a definite outward movement away from the back cover10, in addition to an upward movement. And, during the closing of theterminal enclosure, the guiding and locking slot 38' guides the upperfront cover 14 downwardly and inwardly to engage and properly actuatethe self-locking cam 40.

During such opening and closing movements, the inward and outwardmovements of the upper portion of the upper front cover 14 are much lessmarked and the standard or conventional guiding and locking slots 38, 38are satisfactory thereat.

The side flanges 32, 34 of the upper front cover 14 are each providedwith inwardly directed off-set portions 33, 33 and corner cut-outportions which permit these flanges 32, 34 to nest and to fit within theside flanges 20, 22 of the back cover 10. Such an overlapping, nestingarrangement adds to the tamper-proof and the weather-proof features ofthe terminal enclosure.

The cap 16 has a horizontal-plane cross-section which is approximatelyrectangular or square and is adapted to fit over the upper ends of theback cover 10 and the upper front cover 14, when they are assembled andin use, to protect and cover them and the terminal enclosure from theelements. The cap 16 may be a separate part but, preferably, it ispermanently secured in position to the top of either the back cover 10or the upper front cover 14 to prevent it from being lost or misplacedand to facilitate and to expedite the assembly of the upper front cover14 to the back cover 10.

It is to be realized that, if the laterally projecting lanced tabs,pins, or shoulder rivets 36, 36, 36' and the guiding and locking slots38, 38, 38' were the sole means of holding and locking the upper frontcover 14 in position with respect to the back cover 10 during use,anyone, whether authorized or unauthorized, but with sufficientcuriosity or with vandalism in mind, could easily gain access to theinterior of the terminal enclosure by simply lifting up and removing theupper front cover 14. Such is, of course, highly undesirable. Therefore,an automatically-operable, self-actuating locking means is additionallyprovided to easily and to simply secure and lock the upper front cover14 in position with respect to the back cover 10 during use and toeasily and simply unlock these members to open the terminal enclosurefor service, or maintenance, or for any other purpose. Such is naturallyvery highly desirable to insure the safety and the security and theprotection of the equipment and the parts in the terminal enclosure andto enhance its tamper-proof and vandalism-proof features.

THE IMPROVED SELF-LOCKING DEVICE

As noted primarily in FIGS. 4 and 8, an easily unlocking and opening andsubsequently automatically self-actuating locking device is provided forthe terminal enclosure and comprises, as its main operating elements, arotatable self-locking cam 40 and an actuating tubular shoulder rivet 46having a hexagonal head 48.

The cam 40 comprises a larger main cam portion 41 which somewhat verygenerally resembles a figure-8 configuration and a smaller, cylindricalhub portion 42. The cam 40 and its hub 42 are very securely,non-rotationally mounted on a smaller cylindrical shank portion 44 ofthe tubular shoulder rivet 46 and are adapted to rotate positivelytherewith. If desired, a more positive engagement between theself-locking cam 40 and the shank portion 44 may be employed, such asobtained by the use of splined shafts and fittings, Woodruff keys, andthe like.

The hexagonal head 48 of the tubular shoulder rivet 46 fits within therecess of the walls of an annular cup washer 50. The tubular shoulderrivet 46 also has a larger cylindrical shank portion 52 which isrotatably mounted within a circular opening formed in the flange 36 ofthe back cover 10. The other end of the tubular shoulder river 46 (theleft hand end, as viewed in FIG. 8) is rolled or otherwise peened orflattened back against the surface of the side of the rotatableself-locking cam 40 and prevents slippage between the self-locking cam40 and the tubular shoulder rivet.

The cup washer 50 is provided with a lanced, protruding tab 54 (also seeFIGS. 9 and 10) which fits within an opening 56 formed in the flange 36of the back cover 10 whereby, once the protruding tab 54 of the cupwasher is fitted within the opening in the flange 36 of the back cover10, further rotation of the cup washer 50 is prevented. However, thisdoes not prevent rotation of the tubular shoulder rivet 46 and theself-locking cam 40 and hub 42 securely mounted thereon. Considerationof FIGS. 4 and 8 will reveal that, when the hexagonal head 48 of thetubular shoulder rivet 46 is rotated, the self-locking cam 40 and itshub 42 are correspondingly rotated through the same degree of angularrotation.

The hexagonal head 48 of the tubular shoulder rivet 46 is a standard orconventional size but fits relatively closely within the walls of theannular cup washer 50 with a relatively small amount of clearance. As aresult, a special wrench or other tool having relatively thin walls isrequired to fit into the cup washer 50 to grip and turn the hexagonalhead 48. A standard on conventional size socket wrench or a box-end oropen-end wrench or other standard or conventional wrench or tool cannotfit into the cup washer 50 to grip and turn the hexagonal head 48 of thetubular shoulder rivet 46 and thus the possibility of tampering andvandalism is considerably lessened. The use of this particular type ofhexagonal head 48 and this specific form of security cup washer 50 isnot necessary and any other tamper-proof head style or other securityshape or form may be employed. For example, a tubular shoulder rivet orequivalent element having a pair of small holes in its top surfacesuitable for cooperating with the projecting pins of a spanner wrench orequivalent tool would also be suitable.

It is therefore apparent from FIG. 8 that a person having the requiredspecial wrench or tool capable of fitting within the cup washer 50 andgripping and turning the hexagonal head 48 of the tubular shoulder rivet46 can rotate it and the self-locking cam 40 and hub 42 mounted thereon.Such a simple and uncomplicated actuating means is all that is requiredto set in operation the functioning of the unlocking and opening of theterminal enclosure.

In FIG. 4, the terminal enclosure utilizing the rotatable self-lockingcam 40 is shown in the fully closed or locked position. In such aposition, the long, main axis of the self-locking cam 40 passing throughits center of rotation 0 is shown at an angle of about 16° as measuredclockwise from the vertical direction. This is the specific illustratedconfiguration of FIG. 4 but it is to be appreciated that the fullyclosed or locked position may still be retained with the self-lockingcam 40 at regular positions of from about 12° to about 24° as measuredclockwise from the vertical direction. Other degrees and other ranges ofdegrees are, of course, possible with other shapes and designs of camsand with types and forms of terminal enclosures.

THE ROTATABLE SELF-LOCKING CAM

As noted especially in FIG. 4, the self-locking cam 40 possesses asomewhat generally figure-8 configuration. The self-locking cam 40 iscapable of rotation about its center 0, when so urged by the actuatingtubular rivet 46. The bottom, or farthest-out portion, of theself-locking cam 40 is a relatively smooth curved or arcuate surface 60which, in this particular embodiment, is the arc of a circle having thepoint 0 as its center.

Directly below and facing the curved or arcuate surface 60 of theself-locking cam 40 is a cooperating surface 62 of the upper front cover14 in the form of a lower rear or tab which is formed generallyperpendicularly outwardly from the main material of the upper frontcover 14, as seen more clearly in the perspective view of FIG. 13.

If an unauthorized person were to try to open the terminal enclosure byforcibly pushing upwardly on the upper front cover 14, the lower ear ortab 62 would be moved upwardly to butt against the curved or arcuatesurface 60 of the self-locking cam 40. In FIG. 4, it is to be observedthat the upper surface of the lower ear or tab 62 is inclined downwardlyin a clockwise direction about 7° below the horizontal. The point ofcontact between the upper surface of the lower ear or tab 62 and thelower curved or arcuate surface 60 of the self-locking cam 40 is thus solocated that the external force exerted by the unauthorized person inforcibly lifting the upper front cover 14 is transmitted angularlyupwardly towards the center 0 of the self-locking cam 40, exertssubstantially no rotational force thereon, and merely locks the twosurfaces 60 and 62 together which tends to keep closed and locked theterminal enclosure.

The specific angle of 7° below the horizontal direction is not criticaland it may be increased to 20° or 30° or even more, or it may bedecreased to 0° or even to 20° or 30° or even more above the horizontaldirection, if so desired or required. However, such increased anglestend to introduce clearance difficulties and it is preferred to keepsuch angle in the range of from about 0° to about 15° as measuredclockwise below the horizontal.

It is to be noted that, at all the above angles, the line of thetransmitted forces created by the unauthorized efforts to raise theupper front cover 14 will directly or approximately pass through thecenter 0 of the self-locking cam 40 and that substantially no rotationalforce or couple will be created thereon. As a result, there will be notendency at all on the part of the self-locking cam 40 to rotate ineither direction, much less to tend to open the terminal enclosure.

It is possible, however, that, through the inevitable wear and tear thattakes place on the various parts of the terminal enclosure, or perhapsdue to the fact that the assembly of the various parts of theself-locking device may not have been perfectly precise in everyinstance, or for any other reason, the line of the transmitted forceexerted by the unauthorized efforts to open the terminal enclosure doesnot pass exactly through the center 0 but passes to the right or to theleft of the center 0, as viewed in FIGS. 4-7.

If it passes to the right of the center 0, this will create no problemas such will tend only to create a rotational force in the nature of acouple tending to rotate the self-locking cam 40 in a counterclockwisedirection which tends to close or to keep closed the terminal enclosure.

On the other hand, if the line of the transmitted force were to pass tothe left of the center 0, although such would tend to create arotational force in the nature of a couple tending to rotate theself-locking cam 40 in a clockwise direction tending to open theterminal enclosure, such couple is not large enough in magnitude as toovercome the frictional, inertial, or other forces tending to keep theself-locking cam at rest.

It is thus seen that the upper front cover 14 can be securely held in aclosed and locked condition on the back cover 10 and is capable ofresisting unauthorized efforts made externally of the terminal enclosureto open it, unless the person seeking to open it has the necessaryspecial wrench or tool. The interior of the terminal enclosure is thusdeemed to be safely locked and secure.

THE OPENING OPERATION

If it is desired to move the upper front cover 14 upwardly and then tothe right, as viewed in FIGS. 4-7, in order to unlock and to open theupper compartment of the terminal enclosure for service, maintenance,inspection, or for any purpose whatsoever, such is accomplished by arelatively simple and easy procedure.

A special wrench or tool is fitted within the recess of the cup washer50 to grip the hexagonal head 48 of the tubular shoulder rivet 46 and toturn it and the self-locking cam 40 mounted thereon in a clockwisedirection, as viewed in FIGS. 4-7.

The first rotational movement of the self-locking cam 40 takes up anyslack which may be present. It most cases, it will be about 0°, orperhaps a very low angular value. In FIG. 4, as drawn, it is about 6°and, as shown in FIG. 5, the slack is very quickly taken up and anactuating cam surface 66 on the self-locking cam 40 is rotated to buttagainst the corner of an upper ear 68 of the movable upper front cover14. Up to this time, the movable upper front cover 14 has not movedupwardly or in any direction.

The next clockwise rotational movement of the self-locking cam 40forcibly elevates the upper ear of the movable upper front cover 14, asshown in FIG. 6, whereby the upper front cover 14 moves upwardly in anopening direction. Also, due to the nature and the curvature of theactuating cam surface 66, the movable upper front cover 14 movesslightly to the right, which is also in the opening direction. By thistime, the self-locking cam 40 has rotated through a substantial anglewhich, in FIG. 6, is about 69°.

A lower projecting end portion 70 of the movable upper front cover 14which is immediately adjacent the upper ear 68, however, continues toride against the surface of the outer periphery of the hub 42 of theself-locking cam 40 and thus further movement of the movable upper frontcover 14 to the right or in the opening direction is restricted. Theterminal enclosure is therefore only partially open at this point in theconfiguration shown in FIG. 6. And, of course, it is still in a lockedcondition.

It is also to be observed that, during this time, the main body of therotatable self-locking cam 40 has been rotating or moving out of the wayof the upwardly-moving surface 62 of the upper front cover 14, so thatthe lower locking surface 60 of the self-locking cam 40 no longer is ina position as to hold and prevent further upward movement of the upperfront cover 14. Such action takes place simultaneously and automaticallywith the rotational movement of the self-locking cam 40.

Continued additional angular rotation of the self-locking cam 40 by theactuating tubular shoulder rivet 46 continues to forcibly elevate theupper ear of the upper front cover 14, as now shown in FIG. 7, wherebythe upper front cover 14 continues to rise upwardly and to move to theright until the lower projecting end portion 70 of the upper front cover14 is high enough to slide over the top of the outer cylindricalperiphery of the hub 42 of the self-locking cam 40.

As a result, the upper front cover 14 is unlocked and is released fromthe grip of the hub 42 of the self-locking cam 40 and is free to bemoved to the right as far as desired to remove the upper front cover 14from the back cover 10, and, of course, to open the interior of theterminal enclosure for service, maintenance, etc.

By this time, the self-locking cam 40 has been rotated by the actuatingtubular shoulder rivet 46 through a total angle of about 90° but it isto be pointed out that this specific angle of 90° is not essential orcritical in any way. It is actually more dependent upon the nature andphysical characteristics and shape of the cam surface 66 of theself-locking cam 40, the configuration and the positioning of the upperear 68, the shape and the length of the projecting end portion 70 of theupper front cover 14, the diameter of the hub 42 of the self-locking cam40, and so forth. Other designs of such elements can be used to decreasesuch required rotational angle to as little as about 50° or, if desired,increase it to as much as about 150°, or more. Lower degrees of angularrotational movement are normally preferred.

Additional rotational movement of the self-locking cam 40 by theactuating tubular shoulder rivet 46 beyond the position shown in FIG. 7will forcibly urge the upper front cover 14 even more in the right handor opening direction, whereby the lower edge of the upper front cover 14will be pushed even more away from the back cover 10, thus providingplenty of room and finger space for the workman to grasp the lower edgesof the upper front cover 14 to remove it from the back cover 10. Thehazard of finger-pinching or finger-nail crushing is therefore virtuallyeliminated.

It is thus seen that all that is required in order to unlock and openthe terminal enclosure is to insert the special wrench or tool into thecup washer 50 to grip and turn the actuating tubular shoulder rivet 46through the required angle, whereby the upper front cover 14 is freed ofall the restraints holding it in a closed or locked condition and iscapable of being simply and easily removed from the back cover to openthe terminal enclosure.

The extent of the movement of the upper front cover 14 upwardly and tothe right, as created by the rotation of the self-locking cam 40,depends upon the relationship of the various mechanical parts andelements previously mentioned and is normally in the range of an upwardmovement of from about 5/16 inch to about 13/16 inch and a right-handmovement of from about 1/8 inch to about 11/4 inches. In the specificcase of the preferred embodiment, as shown in the drawings, thesemovements are, respectively, about 7/16 inch and from about 1/6 inch toabout 7/8 inch, depending on the extent of the rotation of theself-locking cam 40 by the special wrench or tool beyond the positionshown in FIG. 7. All these measurements are taken at the lower edge ofthe upper front cover 14 which is normally the place where the workmanwill grasp the upper front cover 14 in order to open the terminalenclosure.

For reasons which will become clearer from a further reading of thisspecification, it is normally desired that the rotation of theself-locking cam 40 be kept within certain limits, so that, when theupper front cover 14 is removed from the back cover 10, the self-lockingcam 40 is either in the position shown in FIG. 7, or within a prescribeddegree of angularity from such position, as limited by means providedfor such purpose. This is done so the subsequent closing and locking ofthe terminal enclosure place easily, simply and without requiringspecial adjustment.

This is accomplished by means of a feature on the cup washer 50 and thetubular shoulder rivet 46, as best shown in FIGS. 9-12. The cup washer50 has a central opening 74, through which the tubular shoulder rivet 46is adapted to pass. This central opening 74 is provided with anadditional arcuate or semi-annular cut-out portion 76. And the tubularshoulder rivet 46 is provided with an additional spur or tab 74 which isadapted to fit slidably in the arcuate or semi-annular cut-out portion76.

The cup washer 50 is locked to the back cover 10 and is prevented fromrotating by the tab 54 fitting within the opening 56 in the back cover10. The larger shank 52 of the tubular shoulder rivet 46 with the tab 78thereon is rotational but its rotation is limited by the extent of thesliding movement of the tab 78 in the semi-annular cut-out portion 76.As shown in FIG. 10, the cut-out portion extends for about 180° but suchangle is not critical and may be in the range of from about 50° to about270°, depending upon the particular circumstances and conditions whichare involved. Normally, however, a range for the cut-out portion 76 isin the range of of from about 150° to about 210°.

THE CLOSING OPERATION

After the upper front cover 14 has been removed and the necessary work,servicing, maintenance, etc., has been completed, a very simpleprocedure is instituted in replacing and re-locking the upper frontcover 14 to close and lock the terminal enclosure.

The upper front cover 14 is returned to the position shown in FIG. 7and, if its weight is sufficient, it is simply allowed to drop inwardlyand downwardly under the force of gravity to the closed and lockedposition of FIG. 4. However, if the weight of the upper front cover 14is insufficient, or if the particular enclosure is not in a verticalposition whereby the force of gravity cannot be utilized, then the upperfront cover 14 is given a light push to institute the automatic andself-actuating closing operation. As will be seen, this downwardmovement is all that is required to close and lock the terminalenclosure. No additional other actions are required.

First, the upper ear 68 of the movable upper front cover 14 buttsagainst the slanting cam surface 66 which, as described previously isnormally always in the angular position shown in FIG. 7, or not toodistant angularly therefrom, as limited by the arcuate slot 76 and thetab 78 sliding therein. The self-locking cam 40 is then forcibly rotatedby the upper ear 68 in a counterclockwise direction, as viewed in FIGS.5-7, to pass through the angular position shown in FIG. 6, wherein it isnow partially closed, rather than partially open. The rotation continuesfor the self-locking cam 40 to the angular position shown in FIG. 5wherein the terminal enclosure is considered fully closed and securelylocked.

It occasionally happens that, during the time that the workman isworking on the equipment inside the terminal enclosure, the self-lockingcam 40 is rotated counterclockwise from the position shown in FIG. 7,such as by accidentally pushed or knocked by the workman, so that it isin an angular position similar to that of FIG. 4, at the time that theworkman starts to close the terminal enclosure by re-positioning theupper front cover 14 and giving it a light push to institute the closingoperation.

This time, it is the lower ear 62 of the upper front cover 14 that buttsagainst the back face or rear surface of the self-locking cam 40 torotate it in a clockwise direction to approximately the angular positionof FIG. 6 and, from then on, the closing operation proceeds aspreviously described.

And that is all that is required for the closing operation which, asnoted, proceeds automatically and in self-actuating fashion, once themovable upper front cover 14 is placed in the proper position.

During such self-actuating rotation of the self-locking cam 40, the thecurved lowermost surface 60 of the self-locking cam 40 swings downwardlyfrom its outermost position of FIG. 7, through its intermediate positionof FIG. 6, to end up in the angular position shown in FIG. 5 wherein itis again in position as to be capable of blocking and preventing anyupward movement of the upper front cover 14, if and when such upwardmovement is brought about by someone who does not have a special wrenchor tool and is merely physically pushing on the the upper front cover 14in an upward direction in an effort to gain unauthorized access to theinterior of the terminal enclosure.

The lowermost closed position of the upper front cover 14 is determinedeither by an arcuate portion 67 of the upper front cover 14 coming torest on the top of the hub 42, or by the pins 36, 36, 36' coming to restat the deepest end of the slots 38, 38, 38'. In any event, the lowerportion 70 of the upper front cover 14 is well below the top surface ofthe hub 42 to prevent an opening movement to the right and the lowermostcurved surface of the self-locking cam 40 opposes the lower ear 62 ofthe upper front cover 14 to prevent any upward opening movement.

THE MODIFICATION OF FIGS. 14-18

A modification of the embodiment of the improved self-locking device ofFIGS. 1-13 is shown in FIGS. 14-18, wherein a modified rotatableself-actuating and self-locking cam 140, having a somewhat L-shapedfigure, is shown mounted on a normally stationary back cover 110 of aterminal or other enclosure. The rotatable self-locking cam 140 ispivoted at a point 100 and is adapted to be rotated thereabout. Therotatable self-locking cam 140 is formed with a generallysemi-cylindrical hub portion 142, and an L-shaped actuating or camportion comprising a side actuating cam surface 166, and a lower,relatively smooth, curved or arcuate surface 160 which, in thisparticular embodiment, is the arc of a circle having the pivot point 100as its center.

The side actuating cam surface 166 of the rotatable self-locking cam 140cooperates with a downwardly projecting end portion or ear 170 of arelatively movable upper front cover 114 of the terminal enclosure tounlock and free the upper front cover 114 from the stationary back cover110. Consideration of FIGS. 14-16 will make clear the operation of thisembodiment of the invention.

THE FULLY CLOSED AND LOCKED POSITION

In FIG. 14, both the rotatable self-locking cam 140 mounted on thestationary back cover 110 and the downwardly projecting arcuate endportion or ear 170 of the movable upper front cover 114 aresubstantially in the positions they assume when the upper front cover114 is in its fully closed and locked position on the stationary backcover 110.

At such time, the upper front cover 114 can be forcibly moved or jiggledup and down slightly to a relatively small degree but the contactbetween the curved or arcuate surface 160 of the rotatable self-lockingcam 140 with an opposed surface 162 on the movable upper front cover 114limits and stops the upward movement of the upper front cover 114 toprevent its opening and unlocking.

This is accomplished by the same basic procedures and principlespreviously described in connection with the embodiment of the inventionillustrated in FIGS. 1-13. When an unauthorized or curious person triesto open the terminal enclosure by forcibly pushing upwardly on the upperfront cover 114, the surface 162 moves vertically upwardly a shortdistance to butt against the curved or arcuate surface 160 of theself-locking cam 140. However, the line of force created and transmittedby such a forceful effort is directed at the pivot point 100 of therotatable self-locking cam 140, due to the arcuate nature of the curvedsurface 160. Consequently, no rotational force, or torque, or couple isdeveloped or exerted to rotate the self-locking cam 140 which isrequired to open and unlock the terminal enclosure.

Again, it is not essential that the line of transmitted force passprecisely through the pivot point 100. If the line of transmitted forcepasses to the right of the pivot point 100, as viewed in FIGS. 14-16, arotational force, torque, or couple is created of a very small magnitudewhich actually tends to rotate the self-locking cam 140 in acounterclockwise direction which tends to keep the terminal enclosure ina fully closed and locked condition. And, as pointed out previously, ifthe line of transmitted force were to pass to the left of the pivotpoint 100, then the rotational force, torque, or couple which would becreated would be very small and would not be large enough in magnitudeas to overcome the frictional, inertial or other forces tending to keepthe self-locking cam 140 at rest.

It is possible, nevertheless, that, if the jiggling of the upper frontcover 114 were to be continued for an extended period of time, and forceor pressure in an upward direction were to be continuously exerted onthe upper front cover 114, that the self-locking cam 140 could slowlyand gradually begin to rotate and then continue to rotate until finallyand eventually, it would rotate by means of very small increments to asufficient degree wherein the upper front cover 114 would be unlockedfrom the back cover 110 and be free to be opened. This, of course, isvery undesirable.

This is avoided in the present inventive concept by forming asubstantially vertically disposed, relatively short, flat, planarsurface 168 on the generally semi-cylindrical hub 142 of theself-locking cam 140. This flat, planar area 168 directly faces anothersubstantially vertically disposed, flat, planar surface 169 on theupper, inner part of the projecting arcuate end portion 170.

If the jiggling of the upper front cover 114 were to be continued for anextended period of time with continuously applied force or pressure onthe upper front cover 114 in an upward direction, then the flat surface169 contacts the flat surface 168 and effectively prevents any rotationof the self-locking cam 140 and permits only a sliding movement of theself-locking cam 140 in the vertical direction. As a result, the upperfront cover 114 can move only in a vertical direction, along with thevertical movement of the self-locking cam 140, and there will be nopossibility of the upper front cover 114 being jiggled sufficiently asto be finally and ultimately removable from the back cover 110.

Forced downward movement of the upper front cover 114 is limited andstopped by contact between a curved surface 165 located at the uppermostpart of the hub portion 142 of the self-locking cam 140 and an opposedcurved surface 167 on the upper front cover 114. In such aconfiguration, as noted in FIG. 14, therefore, the upper front cover 114is limited and stopped in its vertical movements and is not removable insuch directions from the back cover 110, except by procedures known toauthorized persons. The terminal enclosure is closed and lockedsecurely.

And, of course, horizontal movement of the upper front cover 114 to theleft or to the right, as viewed in FIGS. 14-16, is limited and stoppedby contact between the self-locking cam 140 and the projecting endportion 168 and 170 to the left and by the main portion of the upperfront cover to the right. It is therefore seen that the upper frontcover 114 is closed and securely locked against movements in alldirections.

THE OPENING OPERATION

Rotation of the self-locking cam 140 in a clockwise direction, as viewedin FIG. 14, from its fully closed and locked position, to the positionof FIG. 15 causes the actuating cam surface 166 to move against the endportion or ear 170 of the upper front cover 114 and force it upwardly ina first or opening direction, as shown. At the same time, the curved orarcuate surface 160 of the self-locking cam 140 is rotated clockwise andmoves out of the way of the upwardly moving surface 162 of the upperfront cover 114, and thus does not limit or stop its upward movement.

Continued clockwise rotation of the self-locking cam 140 to the positionof FIG. 16 causes the upper front cover 114 to be moved even fartherupwardly in the unlocking and opening direction. And, at the same time,the arcuate surface 160 of the self-locking cam 140 moves completely outof the way of the upwardly moving surface 162 of the upper front cover114, which is thus permitted to move upwardly to the full extentrequired for opening.

In FIG. 16, therefore, the upper front cover 114 has moved upwardly allthat is necessary and is completely unlocked from the back cover 110 andis free to be moved to the right, as viewed in FIG. 16, to open theterminal enclosure.

The upper front cover 114 is then completely removed from the back cover110 and workmen or other authorized personnel are able to work orperform other functions and duties in the interior of the terminalenclosure.

THE CLOSING OPERATION

Closing and locking of the terminal enclosure is accomplished byreversing the directions of the movements and rotations of FIGS. 14-16.The upper front cover 114 is brought back to the left, whereby the hub142 of the self-locking cam 140 enters the L-shaped opening in the upperfront cover 114 between the ear 170 and the opposed surface 162. The hub142 then enters the L-shaped opening, as the upper front cover 114 ismoved more to the left. The ear 170 and the actuating cam surface 166meet but, this time, the ear becomes the actuating force and forces thecam surface 166 to move downwardly and to rotate the self-locking cam140 in a reverse or counterclockwise direction. The position of FIG. 15is then quickly reached in this closing movement and, in the same way,the position of FIG. 14 is also reached, which is now the fully closedand locked position. All this is very simply and automaticallyaccomplished by merely moving the upper front cover 114 to the left tothe proper extent and then downwardly. Once started, the entire closingoperation is self-actuating and automatic.

The terminal enclosure is again fully closed and locked and again defiesany unauthorized effort to open and unlock the same, except byprocedures and with a special opening wrench or other tool, aspreviously described herein.

THE MODIFIED OPENING ACTUATING MEANS

Such opening and unlocking procedures with the modified self-locking cam140 may also be accomplished by means of modified structure whichdiffers from that previously described with reference to FIGS. 1-13.

As shown in FIGS. 17 and 18, a modified rotatable actuating shaft 146, amodified rotatable cup washer 150, and a fixed, nonrotatablerotation-limiting plate or bracket 154 are the principal elementsemployed in such modified embodiment.

The modified actuating shaft 146 comprises a standard or conventionalhexagonal head 148, a cylindrical shoulder 152, a shank 144 and an endportion 147 having regular equilateral, equiangular hexagonalcross-sections, and a cylindrical shank 145 having a smaller diameterthan the adjacent and surrounding shank 144 and end portion 147.

The cup washer 150 is an annular member which has a circumferential lipor wall and a centrally-located circular opening but does not possessthe additional arcuate or semi-annular cut-out portion 76 or the tab 54of the previously described cup washer 50. The cup washer 150 is thusable to fit on to the shoulder 152 of the actuating shaft 146 inasmuchas the circular opening 174 is slightly larger than the diameter of theshoulder 152 and is also free to rotate on such shoulder 152, whenmounted thereon.

As noted previously, the hexagonal head 148 of the actuating shaft 146has a standard or conventional size but fits relatively closely withinthe upstanding lip or wall of the annular cup washer 150 with arelatively small amount of clearance. As a result, a special wrench orsimilar thin walled tool is required to fit between the heagonal head146 and the lip or wall of the cup washer 150 in order to grip and turnthe actuating shaft 146.

THE ROTATION-LIMITING PLATE

The rotation-limiting bracket or plate 154 (see FIG. 17) is generallyrectangular in shape and possesses a key-shaped hole or slot 131 havinga larger opening 133 and a smaller opening 135. The larger opening 133is larger than the diameter of the end portion 147 of the actuatingshaft 146 so that the actuating shaft 146 may enter the larger opening133 to a desired depth, such as one in which the smaller opening 135 isopposite the cylindrical shank 145. The smaller opening 135 has adiameter slightly larger than the diameter of the cylindrical shank 145,so that the shank 145 can be fitted snugly in the smaller opening 135.

An offset edge portion 129 is provided at one end of therotation-limiting plate 154 thus creating an offset section 127 for ause and purpose to be described in greater detail hereinafter.

The manner in which these individual elements are assembled and thensecured together and fastened in place will help to clarify theirsubsequent operation, function, and use.

The smaller diameter portions 147, 145, 144 and 152 of the actuatingshaft 146 are passed through the centrally-located opening 174 of theannular cup washer 150 which smoothly and rotatably fits on thecylindrical shoulder 152 directly under the hexagonal head 148 of theactuating shaft 146. The shank portion of the actuating shaft 146 andassembled annular cup washer 150 is passed through a circular opening inthe side wall of the back cover 110. The thickness of the wall of theback cover 110, plus the thickness of the cup washer 150 approximatelyequals the length of the cylindrical shoulder 152 of the actuating shaft146 which, at the moment, can rotate in the circular openings of theback cover 110 and the cup washer 150, with the hexagonal shank 144, thecylindrical shank 145, and the hexagonal end portion 147 protruding intothe inside of the terminal enclosure.

The rotatable self-locking cam has a hexagonal opening 137 in its hubportion 142 through which the hexagonal end portion 147 and thehexagonal shank 144 are fitted in a driving, non-rotational relationshipso that the hexagonal opening of the self-locking cam 140 fits snugly ofthe hexagonal shank 144 to be driven thereby and to rotate therewith.

The rotation-limiting plate 154 is placed over the protruding hexagonalend portion 147 of the actuating plate 146 which easily fits through thelarger diameter opening 133. The rotation-limiting plate 154 is placedopposite the cylindrical shank 145 and is then moved laterally, or tothe left, as viewed in FIG. 18, so that the smaller diameter cylindricalshank 145 slips into the smaller diameter opening 135 and is lockedtherein between the larger diameter hexagonal end portion 147 and thelarger diameter hexagonal shank 144.

A circular opening 139 is provided in the rotation-limiting plate 154which is so positioned as to be aligned with and correspond to a similaropening in the side wall of the back cover 110, whereby the openings 139and the opening in the back cover can be aligned and then riveted,bolted, or otherwise secured in position together, as shown in FIG. 18,whereby the rotation-limiting plate 154 and the back cover 110 areactually brought together in contacting relationship by the rivet, bolt,or other fastening element to securely position the rotation-limitingplate 154 in a fixed position on the back cover 110. The angularlyoffset portion 129 and the offset section 127 of the rotation-limitingplate 154 which is generally parallel to the side wall of the back cover110 provide sufficient clearance for the self-locking cam 140 to rotatetherebetween. Consideration of FIG. 17 will reveal that the self-lockingcam 140 can rotate between limits fixed by the edges of the offsetportion 129, against which the self-locking cam 140 will rotate andstop. In FIG. 17, the maximum rotation of the self-locking cam 140 isapproximately 170° but such degree of rotation may be increased, ifdesired or required, to as much as 210°, or even in specialcircumstances to 270° by simply moving the offset portion 129 to theright, as viewed in FIG. 17. In a similar way, the rotation of theself-locking cam 140 may be reduced, if desired or required, to 150°, oreven to 50° or less, by moving the offset portion 129 to the left, asviewed in FIG. 17, or by adding fixed stops or limiting elements atselected points, such as by forming or placing bosses or raisedprotuberances on the inner surface of the rotation-limiting plate 154.Such bosses or protuberances can be very small in height and shouldmerely protrude from the rotation-limiting plate 154 by a sufficientamount as to stop the rotation of the self-locking cam 140 but not toreach too far as to contact the opposed surface of the wall of the frontcover 114.

Such a means of controlling and limiting the maximum rotation of theself-locking cam 140 is very positive and fool-proof and is less proneto error or inaccuracy inasmuch as there is a direct contact between theself-locking cam 140 which is to be controlled and limited in itsrotation and the edges of the offset portion 129 which does the actualcontrolling and limiting.

THE MODIFIED OPENING OPERATION

The operation of the self-locking device with particular reference toFIG. 17 is as follows: the self-locking cam 140 is identified as 140-14to specifically co-relate the angular position of the self-locking cam140, as in FIG. 17, to the angular position of the self-locking cam 140of FIG. 14. The lower curved or arcuate surface 160 is thus shown inboth Figures in its lowermost angular position which is the fully closedor locked position.

Rotation of the self-locking cam 140 in a clockwise direction, as viewedin FIGS. 14-17 through an angle of about 62° by means of a correspondingrotation of the actuating shaft 146 will bring the self-locking cam 140to the angular position of FIG. 15, which angular position is not shownin FIG. 17, inasmuch as such could confuse and obscure the clarity andunderstanding of FIG. 17. However, such angular position can be easilyvisualized by reference to FIG. 15.

Further clockwise rotation of the actuating shaft 146 through anadditional angle of about 28°, which now creates a total clockwiserotation of the actuating shaft of about 90°, will bring theself-locking cam to the angular position of FIG. 16, which angularposition is again not shown in FIG. 17 but which can again be easilyvisualized by reference to FIG. 16 which now shows the curved or arcuatesurface 160 in the extreme left-hand position, rather than in thelowermost position such as was shown in FIGS. 14 and 17. As notedpreviously, the upper front cover 114 is now free and is unlocked andcan be removed from the back cover 110 by simply moving it to the right,as viewed in FIG. 16.

During the time that the upper front cover 114 is removed from theterminal enclosure, accidental or inadvertent rotation of theself-locking cam 140 is possible to a maximum rotation wherein thecurved or arcuate surface 160 is uppermost, which angular position isshown in FIG. 17, and thus it is to be realized that the modification ofFIG. 17 will permit a total angular rotation of the self-locking cam 140through a maximum angle of about 170°, which, of course, may be changedto as low as about 50° or less to as much as about 270°, as desired orrequired by circumstances.

As pointed out previously, the total angular rotation of theself-locking cam 140 is kept within specified ranges so that the returnof the upper front cover 114 and its automatic self-closing andself-locking features will be obtained.

This invention provides for a simple, easy closing and locking of theterminal enclosure; renders such closing and locking substantiallyself-actuating and self-locking; permits easy field inspections from adistance to determine if the terminal enclosure is locked, since the mrepositioning of the upper front cover 14 in its lowermost position showsa locked condition; and, further, it virtually eliminates thepossibility of workmen forgetting to close and lock the terminalenclosure after completion of work. If desired, special markings may beplaced on the terminal enclosure to indicate the upper or unlockedcondition and the lower or locked condition of the terminal enclosure.

The present inventive concept will be described in greater detail byreference to the following specific Examples, wherein there aredescribed preferred embodiments of the present inventive concept.However, it is to be appreciated that such Examples are given primarilyfor illustrative purposes and are not to be construed as limitative ofthe broader aspects of the invention.

EXAMPLE I

The self-locking device illustrated in FIGS. 1-13 of the drawings isused for this Example. The back cover is about 48 inches long and has arear wall of about 6 inches and side flanges of about 31/2 inches each(all outside dimensions). The lower front cover is about 24 inches longand has a front wall of about 6 inches and side flanges of about 31/2inches each (all outside dimensions).

The lower front cover is secured to the back cover, with their lowerends about even, and they are buried to a depth of about 19 inches,leaving about 29 inches of the back cover above ground and about 5inches of the lower front cover above ground.

The upper front cover is about 24 inches long and has a front wall ofabout 6 inches and side flanges of about 31/2 inches each (all outsidedimensions). There are slight off-set portions on both the lower frontcover and the upper front cover so that they can nest within the sideflanges of the back cover. The upper front cover is made of 14 gagesteel, is galvanized, and has a weight of about 6 pounds.

The cap has a horizontal-plane cross-section of about 6 inches by 6inches square and has a depth of about 2 inches (all outsidedimensions). The cap fits over the top portions of the back cover andthe upper front cover, when they are assembled in use. The cap issecured to the back cover by riveting to prevent it from lost ormisplaced in service and to prevent persons from merely lifting up thetop to gain access to the terminal enclosure that way. The upper ear ofthe movable upper front cover is formed substantially perpendicularlyout of the main plane of the flange of the upper front cover, so that itprotrudes about 1/8 inch out of such plane.

The lower ear of the movable upper front cover is formed substantiallyperpendicularly out of the main plane of the flange of the upper frontcover, so that it protrudes about 1/8 inch out of such plane. It isabout 7° clockwise downwardly below the horizontal.

The long axis, that is, the longest dimension, of the self-locking camis about 11/16 inch. The diameter of the hub of the self-acting cam isabout 1/4 inch. The curved lowermost surface of the self-acting cam isan arc of a circle having the center of rotation of the self-locking camas a center.

Repeated efforts to unlock and open the terminal enclosure by pushingupwards strongly on the upper front cover fail. The terminal enclosureis closed and locked securely.

A special wrench is fitted into the recess of the cup washer to grip thehexagonal head of the actuating tubular shoulder rivet to turn it,whereby the self-locking cam and its hub are actuated to rotate insimilar fashion. A rotation of about 90° is required to unlock the upperfront cover from the back cover. During such rotation of theself-locking cam, the upper front cover is raised about 1/2 inch and ismoved to the right a distance of about 1/6 inch. Continued rotation ofthe tubular shoulder rivet and the self-locking cam moves the lower edgeof the upper front cover more to the right for a total movement of about7/8 inch. The lower edge of the upper front cover is then gripped by thefingers and is raised and removed from the back cover to open theterminal enclosure.

After the necessary work has been completed inside the terminalenclosure, the upper front cover is returned to approximately theposition of FIG. 7 and is given a light push. The upper front coverslips down into position and the terminal enclosure is closed and lockedsecurely. The special wrench is not required during the closing andlocking of the terminal enclosure. It is automatic and self actuating,once the upper front cover is placed in the proper position and given alight push.

EXAMPLE II

The procedures described in Example I are followed substantially as setforth therein, with the exception that the lower ear of the upper frontcover is disposed substantially horizontally, rather than being inclineddownwardly in a clockwise direction about 7° below the horizontal.Efforts to open the terminal enclosure again fail. The locking actionbetween the lower ear of the upper front cover and the lower surface ofthe self-acting cam is sufficient.

EXAMPLE III

The procedures described in Example I are followed substantially as setforth therein, with the exception that the lower ear of the upper frontcover is disposed at an angle which is inclined upwardly in acounterclock wise direction of about 7° above the horizontal. Efforts toopen the terminal enclosure again fail. The locking action between thelower ear of the upper front cover and the lower surface of theself-locking cam is sufficient.

EXAMPLE IV

The procedures described in Example I are followed substantially as setforth therein, with the exception that, after the necessary work hasbeen completed inside the terminal enclosure and before any effort ismade to close the terminal enclosure, the self-locking cam isdeliberately rotated counterclockwise from the position of FIG. 7 inwhich the major axis of the self-locking cam is at an angle of about 17°downwardly clockwise below the horizontal to a position in which themajor axis of the self-locking cam is at an angle of about 66° upwardlycounterclockwise above the horizontal. This new position isapproximately the angular configuration of the self-locking cam of FIG.5.

No difficulty is encountered in subsequently closing and locking theterminal enclosure. The lower ear of the upper front cover initiallybutts against the rear surface of the self-locking cam and moves itangularly in a clockwise direction until the upper ear of the upperfront cover takes over and completes the closing and locking operation.

EXAMPLE V

The self-locking device of FIGS. 14-18 is used for this Example. Theterminal enclosure is substantially as described in Example I.

The self-locking cam is shown in FIGS. 14-16. It has an overall maximumlength of about 3/4 inch and an overall maximum width of about 1/2 inch.The radius of the arc of the curved or arcuate surface at the lowerportion of the cam is about 9/16 inch and the center of such arc is thecenter of rotation of the self-locking cam. The transmitted forcecreated by an unauthorized pushing of the upper front cover in an upwarddirection will pass substantially through the center of rotation of theself-locking cam and will be ineffectual in an effort to open theterminal enclosure.

The length of the rotation-limiting plate is about 1-9/16 inches and itswidth is about 7/8 inch. The diameter of the larger opening of thekey-hole slot is about 1/5 inch. The diameter of the smaller opening ofthe key-hole slot is slightly greater than 1/8 inch. The diameter of thesmaller cylindrical shank portion of the actuating shaft is about 1/8inch so that is can easily slip into the smaller opening of the key-holeslot and be locked therein. The rotation-limiting plate is riveted tothe inside wall of the back cover. A rotation of about 90° is requiredto unlock the upper front cover from the back cover. The maximumrotation of the self-locking cam is about 170°, as permitted by therotation-limiting plate.

The modified version of the self-locking device performs verysatisfactorily. The results are generally comparable to the resultsobtained in Example I. Repeated efforts to forcibly open and unlock theterminal enclosure by pushing upwardly strongly on the upper front coveror by continued jiggling of the same do not succeed. The terminalenclosure is closed and locked securely. However, by means of a specialwrench which is employed to rotate the actuating shaft, the self-lockingcam is easily rotated and the terminal enclosure is very easily openedto permit access to its interior. The terminal enclosure is very easilyand simply closed by merely bringing the upper front cover to the properposition on the back cover and by pushing it in and down whereby itself-locks by itself, without requiring any special wrench or othertool. The self-locking device is commercially acceptable.

EXAMPLE VI

The procedures described in Example V are followed substantially as setforth therein, with the exception that the rotation-limiting plate ismodified in that the offset portion is moved to the right, whereby therotatable self-locking cam is permitted a maximum rotation of about210°.

The operation of the self-locking device is generally similar to theoperation described in Example V. No difficulty is noted in the openingand unlocking of the terminal enclosure, or in the closing and lockingprocedure.

EXAMPLE VII

The procedures described in Example V are followed substantially as setforth therein, with the exception that the rotation-limiting plate ismodified in that, although the offset portion is retained in the sameplace, a small boss is formed out of the metal of the rotation-limitingplate which extends inwardly to limit the rotation of the rotatableself-locking cam. The initial point of the rotatable self-locking camremains at about the same place, but the boss prevents the rotation ofthe rotatable self-locking cam to exceed about 150°. The operation ofthe self-locking device is generally similar to the operation of ExampleI. There is no difficulty encountered in the opening and unlocking ofthe terminal enclosure, or in the closing and locking thereof. Althoughonly a few specific Examples of the present invention have beendescribed, it is to be recognized that the broader aspects of thepresent invention are not to be construed as limited to the specificdesigns and configurations disclosed therein, but to include variousother equivalent features, as set forth and included in the spirit andthe scope of the appended claims.

What is claimed is:
 1. A self-locking device for locking a movablestructural member to a stationary structural member, or to anothermovable structural member, or for unlocking the same, comprising: afirst structural member; a second structural member which is movable ina first or opening direction; a rotatable self-locking cam and anactuating means therefor capable of rotating said self-locking cam, saidrotatable self-locking cam being rotatably mounted on said firststructural member; a curved surface on said rotatable self-locking cam,capable of contacting and preventing movement of said second structuralmember in said first or opening direction; a cam surface on saidrotatable self-locking cam, capable of contacting and moving said secondstructural member in said first or opening direction; an ear on saidsecond structural member, said actuating means being capable of rotatingsaid rotatable self-locking cam in an angular direction, whereby saidcam surface on said rotatable self-locking cam contacts said ear on saidsecond structural member to forcibly move said second structural memberin said first or opening direction, while said curved surface on saidrotatable self-locking cam is being simultaneously moved out of the wayof said second structural member, due to the angular rotation of saidrotatable self-locking cam to permit the movement of said secondstructural member in said first or opening direction to move and tounlock said second structural member from said first structural member;an angular rotation-limiting plate having surfaces extending into thepath of rotation of said rotatable self-locking cam, with one surfacelocated on one side of the center of rotation of said rotatableself-locking cam and another surface located on the other side of thecenter of rotation and said rotatable self-locking cam and located suchthat said rotatable self-locking cam is capable of rotation of fromabout 50° to about 270° and being mounted on said first structuralmember to contact the sides of said rotatable self-locking cam and limitthe angular rotation of said rotatable self-locking cam during theunlocking and opening of said second structural member within aprescribed degree of angularity, said surfaces being located on saidangular rotation-limting plate such that said rotatable self-locking camrotates between said surfaces and is always in an operative positionwhen in its open position for self-closing and locking of saidself-locking device, and then, said ear on said second structural membersubsequently becoming an actuating means during the closing and lockingof said second structural member to said first structural member andbeing subsequently capable of rotating said rotatable self-locking camin an angular direction opposite to that of said first angulardirection, whereby said second structural member returns to its originalclosed and locked position, wherein it is prevented from movement insaid first or opening direction by said curved surface on said rotatableself-locking cam.
 2. A self-locking device as defined in claim 1,wherein said angular rotation-limiting plate mounted on said firststructural member is capable of contacting said rotatable self-lockingcam and limiting its rotation to an angle of from about 150° to about210°.
 3. A self-locking device as defined in claim 1, wherein saidangular rotation-limiting plate mounted on said first structural memberto contact said rotatable self-locking cam and limit its rotationcomprises a plate having a section offset from and generally parallel toa portion of said first structural member, thus providing spacetherebetween for the rotation of said rotatable self-locking cam.
 4. Aself-locking device as defined in claim 1, wherein said rotatableself-locking cam is provided with a flat surface to contact andcooperate with a corresponding flat surface provided on said ear of saidsecond structural member to prevent rotation of said rotatableself-locking cam, unless the rotation of said rotatable self-locking camis brought about by said actuating means.
 5. A self-locking device asdefined in claim 1, wherein said rotatable self-locking cam is L-shaped.6. A self-locking device as defined in claim 1, wherein said surfaces ofsaid angular rotation-limiting plate are located on an offset portion ofsaid angular rotation-limiting plate.
 7. A self-locking device asdefined in claim 1, wherein said second structural member is separablefrom and completely removable from said first structural member.
 8. Aself-locking device as defined in claim 1, wherein said first structuralmember is a stationary structural member.
 9. A self-locking device asdefined in claim 1, wherein said ear contacts said cam surface duringthe closing and locking of said structural members to forcibly move saidsecond structural member from its open position to its fully closed andlocked position.
 10. A self-locking device as defined in claim 1,wherein said rotatable self-locking cam is mounted on a rotatable shafthaving a fixed axis of rotation.
 11. A self-locking device as defined inclaim 1, wherein said second structural member is a movable upper frontcover on a terminal enclosure. l
 12. A self-locking device as defined inclaim 1, wherein said second structural member is a movable upper frontcover on a terminal enclosure and said first structural member is a backcover of a terminal enclosure.
 13. A self-locking device as defined inclaim 1, wherein said rotatable self-locking cam is mounted on arotatable shaft having a fixed axis of rotation passing through saidfirst structural member and is capable of rotational movementsexclusively.